(CNSNews.com) - Rep. Michael McCaul (R-Texas), chairman of the House Homeland Security Committee, has a few questions for Immigration and Customs Enforcement (ICE) Director John Morton:

How many illegal aliens did you release from U.S. detention centers? Why were those individuals being detained in the first place? And how do you intend to monitor and track them now that they're free?

In a letter to Morton on Wednesday, McCaul said he was "concerned" to learn that ICE -- using the looming sequester as an excuse -- had released a "large number of detained persons."

"This decision reflects the lack of resource prioritization within the Department of Homeland Security and Immigration and Customs Enforcement and is indicative of the Department’s weak stance on national security," McCaul wrote.

McCaul noted that Congress "mandated and provided resources' to maintain 34,000 beds for illegal immigrant detainees, but as of last week, only 30,773 spaces were filled -- "in clear violation of statute."

McCaul also objected to the detainees being releasd without letting congressional oversight committees know about it.

McCaul is giving Morton until March 6 to get back to him with anwers.

In related developments, the Associated Press reported that Gary Mead, an ICE official, announced he was leaving his job with "mixed emotions." That announcement on Tuesday afternoon came just hours after ICE announced that it had started releasing hundreds of illegal aliens on Saturday.

A spokeswoman for the agency, Gillian Christensen, said there was no connection between Mead's announcement to his staff and the decision to release the illegal immigrants.

But White House spokesman Jay Carney said Wednesday that the decision to release the "low-risk, non-criminal detainees" was made without any input from the White House.

Homeland Security Secretary Janet Napolitano warned this week that the Department of Homeland Security -- of which ICE is a part -- might not be able to afford to maintain the 34,000 beds for immigration detainees and that the impending sequester (automatic budget cuts) would hurt the department's core missions.

On Wednesday, ICE announced it had stopped releasing detainees, according to a report in the Arizona Republic.